Retractible air screen for turbojet engines



June 5, 1951 I KELLY 2,555,592

RETRACTABLE AIR SCREEN FOR TURBOJET ENGINES Filed March 19, 1949 3 Sheets-Sheet l INVENTOR.

THOMAS N.KELLY ATTORNEYS T. N. KELLY RETRACTABLE AIR SCREEN FOR TURBOJET ENGINES June 5, 1951 INVENTOR.

THOMAS N. KELLY ATTORN EYS 5 Sheets-Sheet 2 I Filed March 19, 1949 June 5, 1951 v 2,555,592

RETRACTABLE AIR SCREEN FOR TURBOJET ENGINES Filed March 19, 1949 5 Sheets-Sheet 3,

INVENTOR. THOMAS N. KELLY ATTO R NEYS Patented June 5, 1951 RETRACTIBLE AIR SCREEN FOR TURBOJET ENGINES Thomas N. Kelly, Ferndale, Mich., assignor to George W. Smith, doing business as Smith- Morris Company, Ferndale, Mich.

Application March 19, 1949, Serial No. 82,370

3 Claims.

The present invention relates to turbojet engine airplane installations and specifically to retractible screens for the air intake for such motors.

In such installations, the engine mechanism is customarily mounted axially of a tubular structure with the air intake in the form of an annulus surrounding the engine. With the annulus open at its'intake end and of large cross sectional area, air rushing in at high velocity can easily carry in with it debris of one kind or another with disastrous results.

Fixed screens over theinlet are open to various objections; not the least of which is the possibility of icing andconsequent restriction of air flow. Fixed screens also might become clogged by debris.

Among the objects of the present invention is the provision of; means to eliminatesuch. difiiculties by mounting the screens in. such fashion that they are retractible from the air inlet and automatically cleared of any debris which they may have collected.

Another object is the provision of a screen mounting and operating means which allows the screen to be cleared of debris during the screen movement and automatically locks the mechanism at the end of such movement.

Still other objects and advantages will be apparent to those skilled in the art upon reference to the following description and the accompanying drawings in which Fig. 1 is a more or less diagrammatic view showing the screen arrangement.

Fig. 2 is also a diagrammatic view showing relative location of a screen frame and evacuation door.

Fig. 3 is a view in elevation of the screen operating mechanism as viewed from the intake side.

Fig. 4 is a plan view of the screen operating means.

Fig. 5 is a diagrammatic view of the linkage through which the evacuation door is operated screens in active position.

Fig. 6 is a similar view showing the linkage in an intermediate position.

Fig. '7 is a similar view showing the position of the linkage when the screen is retracted.

Fig. 8 is a section on line 88 of Fig. 4, somewhat enlarged.

In the drawings, Fig. 1 indicates the general arrangement of the engine, air intake, air screens and means for operating the latter. The central circular space A is occupied by the engine z and this is surrounded-by the screened annular air intake, the screen being in sections/Bl All of the latter are indicated as being operated by a single motor C driving through a flexible shaft D a plurality of mechanisms-E, each of the latter in turn operating apart of screen sections B.

Fig. 2 showswthe relative, location of ascreen section B and its evacuation door F and also the two positions. each may assume, the door F being in the dotted line position F at about the midway position of, thescreen B, that. is, itis closedand locked when the screen is stationary at either end of its movement but opens and closes when the screen is opened orclosed.

The arrow. indicates direction of air flow.

Referringfirstto Fig. 4 which shows a plan view of the mechanism,,the actuator E consists of a more or less conventional screw jack, the base portion 20. containing a screw and nut adaptedto move. a plunger 20A in or out of the base portion. The plunger 20A is connected at its free end to a crank arm 2| fixed 170.8. short shaft, 2|A (see Fig. 8) mounted in a bearing in a fixed frame member 22. Mounted to rotate freely upon the adjacent end of shaft 2 IA is the eye 23A of the hinge member of door F, the hinge member being the rib 23B forming part of the door structure.

That portion of shaft 21A beyond member 22 has fixed to it in any suitable manner, as by welding, a double crank member 24 having at one end pivoted thereto a link 24A whose other end is pivoted to a crank arm 25 fixed to a shaft 25A, also carried in a suitable bearing in frame member 22, which also serves as a hinging member for one of the screen sections B. The other end of the double crank 24 has pivoted upon it a short link 26 pivoted at its other end to the central portion of a lever arm 21 mounted to swing about a pin 21A carried upon frame member 22. At the free end of arm 21 is pivoted a link 28 which connects with the rib 233 on door F, being hinged thereto through a suitable pin and boss 28A.

The operation of the plunger 20A through its actuation of the double crank 24 will therefore swing the screen B from one to the other of the positions shown in Fig. 2 and simultaneously open and close the door F.

It should be noted that the pin is so formed that the center of that portion in lever 21 is slightly offset from the center of that portion in arm 28 and slightly above the latter when looked at in Figs. 5 and 7. This formation provides for some adjustment but its main function is to provide locking means for the linkage at both ends of the screen movement. Referring to Figs. 5 and '7, it will be seen that the center of pin 26A is slightly below a line 283 drawn from the center of the bearing for arm 28 to the center of pin 21A. This construction provides a toggle, overcenter locking action for the linkage.

As shown in Fig. 3, two of the linkages are connected by means of an universal joint drive 30 and both operated by one actuator E. At the other end of a screen section B the screen B and door F are both mounted on simple hinges, the hinge for the door being shown at the right of Fig. 4.

I claim:

1. In combination with the annular air intake conduit of a jet engine, an air screen in said conduit, said screen consisting of sections swingable from their operative screening position to a position approximately parallel to the axis of the air annulus, a door opening outwardly and located rearwardly of the screen in the-outer wall of said conduit, in position to permit debris to be ejected from said screen through said door, and means for swinging said screen sections and opening and closing said door, said means consisting of motor means, a crank arm actuable thereby, a shaft to which said arm is fixed, said shaft having also fixed thereto a second arm, screen actuating means operable by one end of said second arm and door actuating means operable by the other end of said second arm.

2. In combination with the annular air intake conduit of a jet engine, an air screen in said conduit, said screen consisting of sections swingable from their operative screening position to a position approximately parallel to the axis of the air annulus, a door opening outwardly and located rearwardly of the screen in the outer Wall of said conduit, in position to permit debris to be ejected from said screen through said door, and means for swinging said screen sections and opening and closing said door, said means consisting of motor means, a crank arm actuable thereby, a shaft to which said arm is fixed, said shaft having also fixed thereto a second arm, a link pivoted to one end of said second arm, said link adapted to swing a screen section, a link pivoted to the opposite end of said second arm, a lever of the third class actuated by the latter link, and means operatively connecting the free end of said lever to said door.

3. In combination with the annular air intake conduit of a jet engine, an air screen in said conduit, said screen consisting of sections swingable from their operative screening position to a position approximately parallel to the axis of the air annulus, a door opening outwardly and located rearwardly of the screen in the outer wall of said conduit, in position to permit debris to be ejected from said screen through said door, and means for swinging said screen sections and opening and closing said door, said means consisting of a motor means, a crank arm actuable thereby, a shaft to which said arm is fixed, said shaft having also fixed thereto a second arm, a link pivoted to one end of said second arm, said link adapted to swing a screen section, a link pivoted to the opposite end of said second arm, a lever of the third class actuated by the latter link, and means operatively connecting the free end of said lever to said door, the center of the point of attachment of the latter connecting means being above the center REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,381,705 Vokes Aug. 7, 1945 2,407,194 Vokes sept. 3, 1946 

